Process for preventing shrinkage and felting of wool



United States tent O PROCESS FOR PREVENTING SHRINKAGE AND FELTING OFWOOL John D. Floyd, Wilmington, Del., assignor to Hercules PowderCompany, Wilmington, Del., a corporation of Delaware This applicationrelates to a process for preventing shrinkage and felting of wool.

It is well known in the textile trade that both woven and knitted woolenfabrics shrink excessively on laundering. This shrinkage varies with thetype of weave in the fabric and, in some cases, may run as high as 60%of the original dimensions. Woolen fabrics shrink by two methods; by theso-called relaxation or consolidation phenomenon, and by felting. Theformer is due to the relaxation of tensions introduced during theknitting or weaving operation and is common to all hydrophilic fibets.The latter is due to the unique physical and mechanical properties ofthe wool fiber. The physical property which brings about felting is thescaled surface of the fiber which givesit a low coefiicient of frictionin one direction. This means that when a fabric is subjected tomechanical action, the individual fibers migrate in one direction makingfor a more dense structure, thereby reducing the linear dimensions. Thisdense structure is consolidated by the higher resilience of the fiberswhich is related to their curling or spiraling tendency.

Various treatments such as chlorination treatments, oxidativetreatments, alkali treatments and resin treatments have been used toreduce the felting shrinkage of wool. None of these treatments, however,has been entirely satisfactory. Thus, chlorination treatments requireclose control of conditions to prevent general loss of desirablewool-like character of the fabric made therefrom and reduction of wearqualities. Moreover, chlorination treatments generally result inweakening the fabric and also impart a harsh feel thereto. Oxidativetreatments as with peroxy compounds and permanganate, are likewisediflicult to carry out in a manner such as to achieve adequateresistance to shrinkage without undue fiber damage. Alkali treatments,as with caustic or potash from dry solvents are disadvantageous from thecost standpoint due to the necessity for solvent-recovery systems andother special equipment. 'Resin treatments, such as with methylatedmethylolmelamine and methylated nylon, cause a loss in the subjectiveproperties of the fabric. Such treatments, moreover, require ahigh-temperature cure and a high add-on level to obtain acceptableshrink resistance. This high additive level causes more or lesspermanent fabric stiffening and, in addition, increases the cost.

The principal object of the present invention is the provision of animproved process for preventing shrinkage and felting of wool.

Another object of the invention is the provision of a durable treatmentto prevent shrinkage in woolen fabrics without detriment to thedesirable physical properties of the fabrics.

A further object of the invention is the provision of a process formaking a shrink-resistant wool fabric without the use of oxidizing,reducing, strongly acid or strongly basic chemicals, all of which aredetrimental to the physical properties of the fabric.

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In accordance with the invention, the above and other objects areaccomplished by treating a wool fabric with certain water-solublecationic thermosetting polyamideepichlorohydrin resins to be describedmore fully hereinafter. It has been found that treatment with suchresinsis highly effective for the dimensional stabilization of woolen fabrics.The treatment, moreover, does not add harshness or stiffness to thefabric and does not significantly yellow or otherwise change the colorof the fabric. a

In carrying out the process of the invention, an aqueous solution of thecationic resin is applied to the fabric in any suitable manner as bydipping, spraying, padding or the like. Any desired or convenientconcentration of the aqueous resin solution may be utilized for such ap:plication; however, it has been found that concentrations from about 1%to about 10% are quite satisfactory and these, therefore, are preferred.'The concentration and time of treatment should be such that the fabricabsorbs from about 0.5% to about 10% by weight, based on the dry weightof fabric, of the cationic resin. j Less than 0.5% will not produce thedesired resistance to shrinkage and felting, and more than 10% offers noparticular advantage and, hence, will normally not be used.

After treatment with the cationic resin, the fabric is dried preferablyat about C. for about 5 minutes in an air-circulating oven. The oventemperature is then raised to about C. and the treated fabric given a5-minute cure at this temperature. This short, low-temperature curecycle can easily be handled by ordinary textile processing equipment.While the described temperatures and times are quite advantageous, itwill be appreciated that the invention is not limited thereto and thatdrying and curing may be effected at higher-or lower temperatures, i.e.,fromabout. 40 C. to about C. with a corresponding decrease or increaseinthe duration of treatment.

A particular advantage of the invention is that the treatment may becarried out, under acid, neutral or alkaline conditions, i.e., at pHsfrom about 3 to about 10. The preferred pH range is from about 5 toabout 8. i 1

The cationic thermosetting polyamide-epichlorohydrin resins contemplatedfor use herein comprise a watersoluble polymeric reaction product ofepichlorohydrin and a polyamide derived from a polyalkylene polyamineand a C C saturated aliphatic dicarboxylic acid. It has .been found thatresins of this type are uniquely effective for preventing shrinkage ofwool fabrics without adversely affecting other desirable physicalproperties of the fabric.

In the preparation of these cationic thermosetting resins, thedicarboxylic acid is first reacted with the 'polyalkylene polyamineunder conditions such as to produce a water-soluble polyamide containingthe recurring groups where n and x are each 2 or more and R is thedivalent hydrocarbon radical of the dicarboxylic acid. This water-soluble polyamide is then reacted with epichlorohydrin to form thewater-soluble cationic thermosetting resin.

tylene polyamines and so on may be employed of which the polyethylenepolyamines represent an economically preferred class. More specifically,the polyalkylene polyamines contemplated fonuse mayberepresented aspolyamine sbin which the nitrogen atoms are linked together by groups ofthe formula QQJlzr- Where n is a small integer greater than unityand'the number of such groups in the molecule ranges from two up toabout eight. The nitrogen atoms may be attached to adjacentcarbon atomsin the group -C,,H or to carbon atoms furtheiapart, but not to the samecarbon atom. This invention contemplates not .onlythe u se of suchpolyamines as diethylenetriamine, triethylenetetramine,tetraethylenepentamine, dipropylenetriarnine and the like, which canbeobtained in reasonably pure form, but also mixtures and various crudepolyarnine materials. For example, the mixture of polyethylenepolyamines obtained by the reaction of ammonia and ethylene dichloride,refined only to the extent of removal of chlorides, water, excessammonia and ethylenediamine, is a very satisfactory starting material."The term polyalkylene polyamine" employed in the claims, therefore,refers to and includes any of the polyalkylene polyamines referred toabove 01 to a mixture of such polyalkylene polyamines.

It is desirable, in some cases, to increase the spacing of secondaryamino groups on the polyamide molecule in ordertochange the reactivityof the polyamide-epichlorohydrin complex. This can be accomplished bysubstituting a diamine such as ethylenediarnine, propylenediamine,hexamethylenediamine and the like for a portion of the polyalkylenepolyamine. For this purpose, up to about 80% of the-polyalky-lenepolyamine may be replaced by a molecularly equivalent amount of thediamine. Usually, a replacement of about 50% or less will serve thepurpose.

The temperatures employed for carrying out the reaction between thedicarboxylic acid and the polyalkylene polyamine mayvary from about 110C. to about 25.0? C. or higher at atmospheric pressure. For mostpurposes, however, temperatures between about 160 C. and 210 C. havebeen found satisfactory and are preferred. Where reduced pressures areemployed, somewhat lower temperatures may be utilized. The time ofreaction depends on the temperatures and pressures utilized and-willordinarily vary from about /2 to 2 hours, although shorter or longerreaction times may be utilized depending on reaction conditions. In anyevent, the reaction is desirably continued to substantial com- Dltiflonfor best results.

In carrying out the reaction, it is preferred to use an amount,ofdicarboxylic acid 'sufitcient to react substantially, completely withthe primary amine groups of the polyalkylene polyamine but insufficientto react with the secondary amine groups to any substantial extent. Thiswill usually require a mole ratio of polyalkylene polyamine todicarboxylic acid of from about 0.921 to about 1.2:1. However, moleratios of from about 0.8:1 to about 1.4': 1.may eused with quitesatisfactory results. Mole ratios outside of these ranges are generallyunsatisfactory. Thus, mole ratios below about 0.8:1 result in a gelledproduct or one having a pronounced tendency to gel while mole ratiosabove 1.4:1 result in low molecular weight polyamides. Such productswhen reacted. with ,epichlorohydrin, do not produce resins having thedesired efficiency for use herein.

In converting the polyamide, formed as above described, to a cationicthermosetting resin, it is reacted with, epichlorohydrin at atemperature from about 45 C. to about 100 -C. and preferably betweenabout 45 C. and 70 .C. until the viscosity of a 20% solids solution at25 C. has reached about C or higher on the Gardner-Holdt scale. Thisreaction is preferably carried out in aqueous solution to moderate thereaction. pH adjustment is usually not necessary. However, since the pHdecreases during the polymerization phase of the .wash cycle.

4 action it may be desirable, in some cases, to add alkali to combinewith at least some of the acid formed.

When the desired viscosity is reached, sufficient water is then added toadjust the solids content of the resin solution to the desired amount,i.e., about 10% more or less, the product cooled .to .about 25 C. andthen stabilized by adding sufiicient acid to reduce the pH at leasttoabout 6 and preferably to about 5. Any suitable acid such ashydrochloric, sulfuric, nitric, formic, phosphoric and acetic acid maybe used to stabilize the product. However, hydrochloric acidispreferred.

In the polyamide-epichlorohydrin reaction, it is preferred to usesufficient epichlorohydrin to convert all secondary amine groupstotertiary amine groups. However, more or less may be added to moderate orincrease reaction rates. In general, satisfactory results may beobtained utilizing from about 0.5 moles to about 1.8 moles ofepichlorohydrin for each secondary amine group of the polyamide. It ispreferred to utilize from about 1.0 mole to about 1.5 moles for eachsecondary amine ere-1 29 he po ya ide- "The following examples willserveto illustrate the invention. .Inthese examples the cationicwater-soluble thermosetting polyamide-epichlorohydrin resin utilized wasprepared as follows: Two hundred twenty-five grams (2.18 moles) of,diethylenctriamine and grams of water were placed in a 3-necked flaskequipped with a mechanical stirrer, thermometer and condenser. To thiswas added 290 grams (2.0 moles) of adipic acid. After the acid haddissolved .in the amine, the solution was heatedto 185-200- C. and heldthere for 1% hour. Then vacuum from a water pump was applied to theflask during the period required for the contents of the flask to coolto C. following which 430 grams of H 0 was added. The polyamide solutioncontained 52.3% solids and had an acid number of 2.1.

To 60 grams of-this polyamide solution in a roundbottom flask was added225 grams of H 0. This solution was heated to 50 C. and 12.5 grams ofepichlorohydrin was added dropwise over a period of 11 minutes. Thecontents of the flask was then heated to 60-70" C. until it had attaineda Gardner viscosity of E. Then grams of H 0 was added to the product,and it was cooled to 25 C. Eleven ml. of 3.7% HCl was then added toadjust the pH to 5.0. The product contained 9.0% solids and had aGardner viscosity of C-D.

Example 1 A sample of scoured. carbonized and bleached wool flannelcloth was treated in the following manner with a 5% aqueous solution ofthe cationic thermosetting resin prepared as described above. The dryfabric was padded, double ends, through a room-temperature solution ofthe resin on a IO-inch laboratory padder. The wet pick-up was found tobe 113% (5.6% resin solids based on the dry weight of the cloth). Thetreated fabric was air-dried and cured for 5 minutes at 150 C. afterwhich it was washed for 45 minutes in a 130 F., 0.1% neutral soap wash.After air-drying, the total shrinkage of the fabric was 9.1%. Thiscompared ,to 50% shrinkage for an untreated sample. It should be notedthat these values represent total shrinkage, i.e., relaxation shrinkageplus felting shrinkage. The hand and color of the fabric after washingwere not impaired by the foregoing treatment.

Example 2 The treated sample from Example 1 was given a second wash asdescribed in Example 1, followed by /z-hour room temperaturedry-cleaning cycle, followed by a third The additional shrinkage afterthese treatments was found to be nil.

Example 3 A sample of woolen ,fabric was treated as in Example ,1.

with a 5.1% aqueous solution of the cationic resin prepared as abovedescribed and cured for 5 minutes at 100 C. The wet pick-up was 100(5.1% resin solids based on dry weight of the fabric). It was washed anddried as previously described. The total shrinkage was found to be 6.1%.

Example 4 A sample of woolen fabric was treated with a 3.13% aqueoussolution of the cationic resin prepared as described above and treatedas in Example 3. The wet pick-up was 100% (3.13% resin solids based ondry weight of the fabric). After washing, its total shrinkage was 3.1%.This sample was given four additional launderings. The increasedshrinkage due to the extended laundering was 4.8%, or a total of 7.9%after five laundermgs.

The following example gives comparative results obtained with well-knownresins used commercially for shrinkproofing wool fabrics. In thisexample, samples of woolen fabric similar to those treated in Examples 3and 4 were treated with different commercial resins in accordance withthe following procedure. The commercial resin was padded onto the fabricfrom a cold aqueous solution containing the ammonium sulfate catalyst(5% on resin solids). The fabric was dried 5 minutes and cured 5 minutesat 150 C. The results are shown in the following table.

What I claim and desire to protect by Letters Patent is:

1. A process of treating wool fabrics to prevent shrinkage thereofduring washing which comprises treating the fabric with from about 0.5%to about 10% by weight, based on the weight of the fabric, of a cationicwatersoluble thermosetting resin obtained by reacting a polyalkylenepolyamine having two primary amine groups and at least one secondaryamine group with a C -C saturated aliphatic dicarboxylic acid in a moleratio of from about 0.8 to about 1.4 of the former to about 1.0 of thelatter to form a long-chain polyamide having secondary amine groups, andthen reacting the polyamide with epichlorohydrin in a mole ratio ofepichlorohydrin to secondary amine groups of said polyamide of fromabout 0.5 :1 to about 1.821, and thereafter heating the treated fabricat a temperature from about C. to about 150 C. to cure the resin.

2. A process according to claim 1 wherein the cationic thermosettingresin is obtained by (1) reacting the C C saturated aliphaticdicarboxylic acid with the polyalkylene polyamine at a temperature fromabout 110 C. to about 250 C. to form the polyamide and (2) reacting thepolyamide with epichlorohydrin at a temperature from about C. to about100 C. to form the watersoluble cationic thermosetting resin.

3. A process according to claim 1 wherein the cationic thermosettingresin is obtained by (1) reacting a C -C saturated aliphaticdicarboxylic acid with the polyalkylene TABLE Shrinkproofing of woolfabric with commercial resins Curing Percent Concen- Conditions,Shrinkage Condition 01 Type of Resin tration, Catalyst min. at after1-30 Fabric Weight 150 0. min. Neu- Percent tral WashMelamine-formaldehyde Resin 6.45 Ammonium Sulfate--- 5 7.6 Harsh, sgifi,dis- CO 0T8 Mfithylated melamineformaldehyde Resin (Type 6.51 .do 5 13.7Harsh and stiff- 130-. 4.21 do 5 29.5 Sllghtlystifl. Methylatedmelamineformaldehyde Resin (Type 3.29 -....do 5 31.3 Soft.

130-- 5.14 do a 16 Slightly stifl. Mzgthylated melamineformaldehydeResin (Type 3. 53 do 5 19.1 Do.

Do. 6.07 .--.-do 5 12.2 Rather stiff.

It will be seen from the examples that woolen fabrics treated inaccordance with the process of the invention are dimensionallystabilized through at least five one-halfhour wash cycles. A particularadvantage of the invention is the fact that the treated fabric, afterwashing, is desirably soft, whereas commercial resins such as thoseillustrated in Example 5, lend a harsh, stiff hand to the fabric and/orprovide substantially less dimensional stability in the fabric. The factthat the resins herein disclosed lend a durable soft hand to the fabricis unexpected since the resins themselves form rather brittle films.

Other advantages flowing from the use of the type of resin hereindisclosed in comparison with commercial resins is that it is effectiveat low concentrations, cures independently of pH and at lowertemperatures, ca. 100 0., requires no catalyst and does notsignificantly yellow or otherwise change the color of the fabric.

The term wool fabric as used herein includes any animal hair fabric suchas sheep wool, mohair, cashmere,

camel hair, alpaca wool, vicuna wool, llama wool, cowhair and horsehair.The term also includes fabrics which are 100% animal hair and fabricswhich are blends of animal hair with natural and/or synthetic fiberssuch as cotton, polyacrylonitrile fiber, polyterephthalate ester fibers,polyamide fibers and so on.

While specific embodiments of the invention have been illustrated anddescribed herein, it will be understood that changes and variations maybe made without departing from the scope of the invention as defined inthe claims which follow.

polyamine at a temperature from about C. to about 210 C. to form thepolyamide and (2) reacting the polyamide with epichlorohydrin at atemperature from about 45 C. to about 70 C. to form the water-solublecationic thermosetting resin.

4. A wool fabric having improved resistance to shrinkage, said fabriccontaining from about 0.5% to about 10% by weight, based on the weightof the fabric, of a cured cationic thermosetting resin obtained byreacting a polyalkylene polyamine having two primary amine groups and atleast one secondary amine group with a C -C saturated aliphaticdicarboxylic acid in a mole ratio of from about 0.8 to about 1.4 of theformer to about 1.0 of the latter to form a long-chain polyamide havingsecondary amine groups, and then reacting the polyamide withepichlorohydrin in a mole ratio of epichlorohydrin to secondary aminegroups of said polyamide of from about 0.5:1 to about 1.8:1.

References Cited in the file of this patent UNITED STATES PATENTS2,468,086 Latham et al Apr. 26, 1949 2,595,935 Daniel et al May 6, 19522,696,448 Hammer et al Dec. 7, 1954 OTHER REFERENCES Ser. No, 323,512,Hagedorn (A.P.C.), published Apr. 20, 1943.

1. A PROCESS OF TREATING WOOL FABRICS TO PREVENT SHRINKAGE THEREOFDURING WASHING WHICH COMPRISES TREATING THE FABRIC WITH FROM ABOUT 0.5%TO ABOUT 10% BY WEIGHT, BASED ON THE WEIGHT OF THE FABRIC OF A CATIONICWATERSOLUBLE THERMOSETTING RESIN OBTAINED BY REACTING A POLYALKYLENEPOLYAMINE HAVING TWO PRIMARY AMINE GROUPS AND AT LEAST ONE SECONDARYAMINE GROUP WITH A C3-C10 SATURATED ALIPHATIC DICARBOXYLIC ACID IN AMOLE RATIO OF FROM ABOUT 0.8 TO ABOUT 1.4 OF THE FORMER TO ABOUT 1.0 OFTHE LATTER TO FORM A LONG CHAIN POLYAMIDE HAVING SECONDARY AMINE GROUPS,AND THEN REACTING THE POLYAMIDE WITH EPICHLOROHYDRIN IN A MOLE RATIO OFEPICHLOROHYDRIN TO SECONDARY AMINE GROUPS OF SAID POLYAMIDE OF FROMABOUT 0.5:1 TO ABOUT 1.8:1, AND THEREAFTER HEATING THE TREATED FABRIC ATA TEMPERATURE FROM ABOUT 40*C. TO ABOUT 150*C. TO CURE THE RESIN.